Bone surgery



Jan. 10, 1950 J, co so 2,494,229

BONE SURGERY Filed July 8, 1946 Znmentor v .4 w "w 7 dttorueg Patented Jan. 10; 1956 UNITED STATES PATENT OFFICE BONE SURGERY John G. Collison, Greensboro, N. 0.

Application July 8, 1946, Serial No. 681,934 Claims. (oi. 128-92) The invention relates to bone surgery, and particularly to means for applying an internal fixation plate to a fractured bone.

Internal fixation plates are commonly used in the treatment of certain types of bone fractures, and these plates are connected to the bone fragments by screws which pass through .holes in the metal plates and penetrate the adjacent cortex, and sometimes also the distal cortex, depending upon conditions.

In applying a fixation plate to a bone, a number of screws, on each side of the line of fracture, are employed. If any one of these screws is not exactly centered. with respect to its hole in the plate a pressure will be set up in the bone which frequently results in the decay of the bone immediately adjacent such screw. Likewise, if any one of the screws is driven into the bone at such an angle that it will tend to draw on one of the other screws, pressure will be set up with resulting decay of the bone. The degree and extent of the decay depends upon the degree and the extent of the pressure set-up in the bone, and it often has very serious results.

In accordance with the present practice the accuracy with which the fixation plate is applied, and hence to a considerable extent the success of the operation, depends uponthe personal skill of the surgeon in so applying the screws that no undue pressure will be set up in the bone fragments.

But as is commonly known even the most skillful surgeons are often not skillful in handling and operating mechanical tools. Frequently this is true because the education of the surgeon has not included the mechanical education and experience necessary to the proper handling of mechanical tools, and in other cases it is true because it is common knowledge that some people are so constituted that they simply cannot become skillful in the handling of mechanical tools, regardless of how skillful and brilliant they may be in other arts.

The purpose of the present invention is to so improve the technique of bone surgery in the application of internal fixation plates that the necessity for mechanical skill in the handling of mechanical tools is practically eliminated. In other words, in accordance with the present invention, the technique is such that every one of the screws is necessarily and positively centered with absolute accuracy with respect to its hole in the fixation plate, and every one of the screws, theretofore positively centered, is necessarily driven into the bone perpendicularly to the fixav 2. tion plate, and thereby entirely avoiding the setting up of undue pressure in the bone.

The invention will be clearly understood from the following description, when taken in connection with the accompanying drawings, in which: i

Figure 1 is a perspective view of afractured bone with the fixation plate partly applied thereto, and showing a guide member about to be applied to one of the holes of the fixation plate and a drill about to be introduced into the guide member; I

Figure 2 is a fragmentary elevational view of the guide member appliedto one of the holes; parts being broken away and parts being in section; l v

Figure 3 is a similar vview but showing the drill in the guide member and entering the adjacent cortex a slight distance;

Figure 4 is a fragmentary sectional view with the guide member removed and showing the drill after it has been-driven entirely through the adjacent cortex; V

Figure 5 isa fragmentary sectional view with the previously mentioned parts removed and a screw inserted in an opening of the fixation plate and having a pilot point fitting neatly in the previously drilled hole in the cortex;

Figure 6 is a similar view but showing the screw as having been driven part way into the cortex;

Figure 7 is a similar view but showing the screw driven all the way in so that the cruciate head is seated in the opening of the fixation plate;

Figure 8 is a horizontal sectional view of the drill, taken on line 88 of Figure 1; and

Figure 9 is an end view of the screw.

Referring to the drawings in more detail, numeral l indicates a bone which has been fractured at 2 and reset ready for the application of a fixation plate-3. The plate is preferably curved slightly so that its edges rest on the bone, thereby preventing any tendency of the. plate to rock.

The plate is provided withany desired number of holes 4 to receive'the screwsby which the plate is fixed to the bone fragments on both sides of the fracture. In the specific embodiment illustrated, each of the ,holes has a tapered upper portion 5 leading to a cylindrical lower portion 6, though of course these openings could be of various shapes. p

.Numeral refers to a centering guide memher which has a central cylindrical bore 8 extending throughout .its length, and which has adjacent its lower end a tapered portion 9 leadreason oflthe pa'rts Saand ll] of the guide cooperating with the *parts 5 and 6 of the opening,'the guide will make an exact fit in the opening and will extend from the fixation plate exactly perpendicular thereto, and with the central 'bore' 8' of the guide exactly centered with respect to the opening or hole 4.

The next step is to introduce a drill H, into the central bore 8 of the centering guide, as suggested in Figure 1 and as shown in Figure a.

Also as shown in Figurel3 the diameter of the drill is-substantiallyithersame:asthe diameter 1 of .the central bore' 8 oflithe guide; so that the drill makes .a neat..slidingcand rotating .fit with. the guide. Thus by reason of: theguide'being centered with respecttox thez holeatsofzthe fixation plate, and

the drill being centered with respect to theguide, tl'- .'e pin1ipoin-t 1210f thecdrill. contacts with the bone. at :.a :point i-whichz is necessarily exactly centeredwith respect to the hole-4.

iTheldr-Hlis now turned-to cause it to enter the shone only:.a=yeryzslightidistance, so that its centered position is fixed, and the centering guide .is then removed,lleav.ingiithe parts as shown in Figure .3 .but withith zguide removed from that figure.

The next step is to drill the hole through the' zadiacentieortexiand also. through the distal cortex iii-the conditions'are-suchthat it seems necessary to do so. For the purpose of-illustration the which is a very short tapered threaded portion M and the end of the screw, in advance of the tapered threaded portion, is a cylindrical pilot portion I5. In the drawings this pilot portion is shown as unthreaded, but in actual practice it would have very shallow threads, because the drilled hole in the bone is of slightly greater diameter than the root diameter of the screw l3, so that when the thread l3 enters the bone the :hone willnot reach down-to the bottom of the threads which would cause fragments of the bone to break' off at the sharp edge of the bone thread.

Hence, as the diameter of the drilled hole I is slightly greater than the root diameter of the thread, there will remain a very shallow thread --"on 'thepilo-t portion which fits snugly in the drilled holein the bone.

hole is idrilledthrougmonly theadjacent wall of Zthe cortex,was shoWn iniE'igureA. In drilling thishole'itis of :great importance that thewall of the hole be perfectly cylindricakthroughout its-length and-that its direction be exactly per- .pendiculan-to the' fixati'on plate. In this'drilling t operation, particularly -when the=-surgeon may not be veryeskilled in the :handling andoperation of mechanical tools, --the re--is=- likely to be some wobbling IOfl the dl fll withthdT881111; that the entering end 0f-lthe hole will -become enlarged =and1irregula1'; andnth'e direction of the drill may 'change. iI-o prevent the'se most undesirable resultsgit will be noted' fr'om Figures3, 4, and particularly 8, that the drill flutes do not have any relief. .Drills zare commonlyprovided with flute relief, and hence whenwobbling of the drill occurs the opening is ehlarged and made irregular, but with the di -ill' disolosed herein, without flute reliefg the flute-surface'is cylindrical, and even the hole bord -w'ill remain cylindrical throughout its-extent,-as shown in-Figures 4'and5. And as the drill -necessarilyentered the bone'exactly perpendicular to the p'la'te; it must necessarily follow oneof the screwsfor attaching" the fixation plate. The novehconstruhtion of'the screw, and the methodof its application, are illustrated in Fig- Ur'esBjfiTZarid'Q. 7

Each of these screws has a cruciate head and a jthrea'dedc'ylindrical body 13,- in advance of ,60 when thereis considerable-wobblingof the drill I This pilot portion 15 has oppositely disposed longitudinally extending recesses or pockets l6. These recesses extend from the end of the screw Ethrouglrthe tapered.-portion: l4 and through one or more of the threads= l3x-on the body. These recesses or pockets wherethey {pass through the :taperedportion. id produce a selfetappingscrew, and to improve .the .self-tapping effect the threads on theta-pared portion M- 'haVe'a ground reiief,-='as indicated byrnumeral I! in-Figure'Q, so that the screwswill'enter.theibone more'easily. 'l'he recessesaor pocketswlfi additionally provide relief for the-hone rcl'iipszhy-collecting them therein.

=By reference tOL-FigureSvitwillbe notedthat the-cylindricalpilot portion 1520f the screw. has

substantiall zthe samediameter as. that of the :hole which hasfibeen. drillednn the cortex,:so. that the pilot portion will Imakea snugLfit'in this hole, and hence the screw'itself .will ibe :positively held inaperfectalignment and perfectly. centered with the @drilledihole andzthusi the screw will enter and followztheiexactficourseof the hole,-which is perpendicular to the .fixatiomplate.

'Ihe various :;'steps 1 described hereinbefore 1 in connectionviwithi theifirstscrew are repeated in exactlyathevsame manner with all :ofthe other screwsyzand' aslpreyiouslylmentioned -the screws may ago 7 through only the aadjacent cortex, I as illustrated; or they may alsoigo through the distal cortex, .dependingrupon:conditions, and in either caseethe technique iand'i the :apparatus remain the same, except of course longer screws are used when they are to extend through both cortices.

From: the. foregoing." description it will be apparent that without any mechanical skill on the :partof the surgeondn the'handling of rnechanical --tools,. the :drilli is; exactlyaand :positively' centered with respectto =the holelin ithe'rfixation plate; that the :drillrnecessarily enterstthe hone-exactly perqpendicular to the: fixation-plate, 2 and: that even with: very considerableawobbli-ng *of the drill during the :drilling r-operati'on the resulting hole willibe periectlyrcylindrical throughout its length and will'berperperidicular to the fixation plate throughout its length, by reason' ofthe fact that the flute surfaces beingiwith'out flute relief are cylindrical that theddrilledyhole in the bone and the hole in the fixation. plateare perfectly centered because: the screw has ac'ylindrical' pilot portion which has ia snugiifit in the drilled hole and thetaperd screw head makes a snug fit'with the tapered portion 5 0i. the :hole in the fixation plate.

By reason-of the :fact that each of the screws is exactly centered with'rrespe'ctiato each hole of the fixation .-plate and 43116 fact'that each screw .75 is perpendicular to -the::fixation..;plate, it follows that no undue pressure is set up in the bone, which pressures often cause bone decay resulting in unsuccessful operations.

Having fully described the invention, what I claim is:

1. In bone surgery, a surgical bone screw, said screw having a threaded portion and a cylindrical pilot portion, said cylindrical pilot portion adapted to fit snugly in a hole drilled in the bone cortex, and one or more recesses or pockets provided in said screw and extending from a point in the pilot portion to a point in the threaded portion to provide a self-tapping screw and to receive the bone chips.

2. In bone surgery, a surgical bone screw, said screw having a threaded portion and a cylindrical pilot portion, said cylindrical pilot portion adapted to fit snugly in a hole drilled in the bone cortex, one or more recesses or pockets provided in said screw and extending from a point in the pilot portion to a point in the threaded portion to provide a self-tapping screw and to receive the bone chips, and the threads of the selftapping section having ground relief.

3. In bone surgery, a surgical bone screw, said screw made of metal suitable for bone surgery, a cruciate head on said screw, said screw comprising a threaded portion and a cylindrical pilot portion, said pilot portion adapted to fit snugly in a cylindrical hole drilled in the bone cortex, and one or more recesses or pockets provided in the screw and extending from a point in the pilot portion to a point in the threaded portion to provide a self-tapping screw and to receive the bone chips.

4. In bone surgery the method of applying a fixation plate to the fragments of a fractured bone comprising the steps of drilling a cylindrical hole through the bone cortex centered with respect to a hole in the fixation plate and perpendicular to the fixation plate, and then causing a leading cylindrical portion of a surgical screw to enter the drilled cylindrical hole in the cortex in a position perpendicular to the fixation plate and then driving the screw home.

5. In bone surgery the method of applying a fixation plate to the fragments of a fractured bone comprising the steps of employing a centering guide to start the drilling of a cylindrical hole through the bone cortex centered with respect to a hole in the fixation plate and perpendicular to the fixation plate, then removing the centering guide, then completing the drilling of the cylindrical hole through the bone cortex, and then entering with a neat fit a leading cylindrical portion of a surgical screw in the drilled cylindrical hole in the cortex in a position perpendicular to the fixation plate and then driving the screw home.

JOHN G. COLLISON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,105,105 Sherman July 28, 1914 1,526,182 Rosenberg Feb. 10, 1925 1,831,813 Levedahl Nov. 17, 1931 2,294,303 Jagow Aug. 25, 1942 2,388,482 Haynes Nov. 6, 1945 FOREIGN PATENTS Number Country Date 742,618 France Jan. 4, 1933 Certificate of Correction Patent No. 2,494,229 January 10, 1950 JOHN G. OOLLISON It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 5, lines 6 and 15, before said insert the words and comma said screw made of metal suitable for bone surgery,

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 14th day of February, A. D. 1950.

THOMAS F. MURPHY,

Assistant Gammz'asz'oner of Patents. 

